JP2007277342A - Ink composition for inkjet recording, recording method and record - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition for inkjet recording, excellent in glossy property even on printing paper, having good color reproductivity, and excellent in ejection stability and clogging recovering property. <P>SOLUTION: The ink composition for inkjet recording comprises at least a colorant, water, an alkanediol and a surfactant, wherein the alkanediol comprises a water-soluble 1,2-alkanediol and a poorly water-soluble 1,2-alkanediol and polyorganosiloxane is used as the surfactant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to an ink composition for ink jet recording, which is excellent in glossiness and color reproducibility in various recording media, especially printing paper, and excellent in ejection stability and clogging recovery ability, and its The present invention relates to an ink jet recording method using an ink composition.

BACKGROUND ART An ink jet recording method is a printing method in which printing is performed by causing ink droplets to fly and adhere to a recording medium such as paper. Due to recent advances in inkjet recording technology, inkjet recording methods have been used in the field of high-definition printing that has been realized only by silver salt photography and offset printing. Along with that, high gloss recording media comparable to photographic paper and art paper used in the field of silver salt photography and offset printing, so-called special paper, is used for inkjet recording, and glossiness equivalent to silver salt photography. Ink for ink jet recording that can realize an image having the above has been developed. Ink-jet recording inks have been developed that can achieve image quality comparable to that of silver halide photographs even when plain paper is used.

  As an ink used for inkjet recording, a water-based ink containing water as a main component and containing a colorant and various additives is generally used. As colorants, pigments are superior to dyes in terms of weather resistance such as light resistance, gas resistance, water resistance, and moisture resistance, and therefore pigment-based inks that take advantage of the properties of pigments are being developed. . For example, in JP-A-2005-194500 (Patent Document 1), there is no bleeding by using a polysiloxane compound as a surfactant and adding an alkanediol such as 1,2-hexanediol as a dissolution aid. An ink composition having excellent gloss for special paper is disclosed. Japanese Patent Application Laid-Open No. 2001-72905 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2003-12583 (Patent Document 3) include 1,2-hexanediol which is a water-soluble alkanediol and slightly water-soluble alkanediol. An ink having a certain amount of 1,2-octanediol added to the ink and having less bleeding with respect to plain paper is disclosed. Japanese Patent Application Laid-Open No. 2005-263970 (Patent Document 4) includes a acetylene glycol compound and a polysiloxane compound as surfactants, and further uses 1,2-octanediol to achieve high printing on plain paper. An ink composition capable of achieving a concentration is disclosed.

  By the way, in recent years, with the spread of image forming technology from digital data, the need for digital color proof (DTP) is increasing especially in the printing field, and the inkjet recording method is also being applied to DTP. Since DTP requires color reproduction and stability reproduction of printed matter, when producing a proof by an ink jet recording method, a special paper for ink jet recording is usually used. However, as a color proofing application, there is a high demand for printing paper, and if it can be output directly to printing paper without using dedicated paper and used as a final proof sample, the cost of proofreading can be greatly reduced. The main printing paper is coated paper with a layer that accepts oil-based ink on its surface, and since the ink absorption capacity of the coating layer is poor, an aqueous pigment ink generally used for inkjet recording is used. If used, the permeability of the ink into the recording medium is low, and the image may be blurred or uneven.

For such a problem, when a highly permeable ink containing the above polysiloxane surfactant and 1,2-hexanediol as a dissolution aid is used, bleeding is improved. Color reproduction and stable reproducibility with the proof and the final printed matter may be a problem.
JP 2005-194500 A JP 2001-72905 A Japanese Patent Laid-Open No. 2003-12583 JP 2005-263970 A

Summary of the Invention

  The present inventors recently added a combination of two specific types of alkanediols and a polyorganosiloxane compound as a surfactant to the ink, thereby improving glossiness in various recording media, particularly printing paper. The inventors have obtained knowledge that an ink composition that is excellent in color reproducibility and excellent in ejection stability and clogging recovery can be realized. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide an ink composition for ink jet recording which has excellent glossiness and color reproducibility, and excellent discharge stability and clogging recovery properties in various recording media, particularly printing paper. It is to provide.

The ink composition for ink jet recording according to the present invention is an ink composition for ink jet recording comprising at least a colorant, water, alkanediol, and a surfactant.
The alkanediol comprises a water-soluble 1,2-alkanediol and a poorly water-soluble 1,2-alkanediol;
The surfactant is a polyorganosiloxane.

  According to the present invention, it is possible to realize an ink composition for ink jet recording that has excellent gloss and good color reproducibility on various recording media, especially printing paper.

Detailed description of the invention

  The ink composition for ink jet recording according to the present invention contains a colorant, water, alkanediol, and a surfactant as essential components. As the alkanediol, a water-soluble 1,2-alkanediol and Two types of alkanediols, which are poorly water-soluble 1,2-alkanediols, and polyorganosiloxane as the surfactant are used. Hereinafter, each component will be described.

<Alkanediol>
The alkanediol used in the ink composition for ink jet recording according to the present invention contains at least two types of alkanediols, a water-soluble 1,2-alkanediol and a poorly water-soluble 1,2-alkanediol. By using these two specific types of alkane diols together with the surfactants described below, an image having excellent gloss and color reproducibility even on a recording medium whose surface is coated with a resin, such as printing paper. Can be realized. Further, even when applied to plain paper, the show-through is improved, so that it can be suitably used for double-sided printing. The reason for this is not clear, but can be considered as follows.

  As described above, 1,2-hexanediol and 4-methyl-1,2-pentanediol are preferably used as the highly permeable ink used in conventional ink jet recording in order to reduce the surface tension and improve bleeding. It is used. However, in order to add only water-soluble 1,2-alkanediol such as 1,2-hexanediol to make the surface tension extremely low, a large amount of addition is required. For example, the surface tension of a 15 wt% aqueous solution of 1,2-hexanediol or 4-methyl-1,2-pentanediol is 25 to 26 mN / m. This increases the viscosity of the ink, thereby reducing the ink weight of the dots. For this reason, it becomes difficult to precisely control the ink weight of the dots, and if the ink is ejected from the head, the landing position may be deviated or misted, or printing durability may be poor. As a result, color developability is deteriorated, graininess is deteriorated, agglomeration unevenness and intercolor bleeding may occur, and this causes a printing defect. On the other hand, the addition of only poorly water-soluble 1,2-alkanediol such as 1,2-octanediol may cause poor printing due to separation of the poorly water-soluble 1,2-alkanediol in the ink, particularly at low temperatures. Also, the storage stability at low or high temperatures may be inferior. On the other hand, when the ink is dissolved using an acetylene glycol surfactant as in the ink described in JP-A-2005-263970, the storage stability at high temperatures may be inferior.

In addition, when ink droplets adhere to the recording medium, there is a transient penetration period in which the surfactant permeates into the recording medium with priority and the relative amount of surfactant in the ink droplets remaining on the surface of the recording medium is lacking. To do. In this transient permeation period, the surface tension of the ink rises rapidly, so that the ink does not penetrate completely into the recording medium and overflows, causing aggregation spots and poor drying. In particular, when the ink containing the conventional alkanediol to be applied to the printing paper, thin ink-receiving layer, as compared with the ink jet recording special paper, due to the low ink absorption into the recording medium, the ink per 1inch / m ² It is considered that the weight (coloring material amount) decreases and the color reproducibility deteriorates. In the present invention, the relative amount of the surfactant is lacking by adding two specific types of alkanediols, a water-soluble 1,2-alkanediol and a slightly water-soluble 1,2-alkanediol. Even during the transitional penetration period, the rapid increase in surface tension is suppressed, and by containing an oleophilic poorly water-soluble alkanediol, due to the affinity with the printing paper having an oil-based coating layer, poor penetration Overflow, aggregation spots, and poor drying can be reduced.

  Further, an ink composition containing a large amount of a water-soluble penetrant such as water-soluble 1,2-alkanediol may be inferior in color developability due to its remarkable penetrability on plain paper. By appropriately emulsifying and completely dissolving an oily substance such as 2-alkanediol with a water-soluble penetrating agent such as a water-soluble 1,2-alkanediol, it is possible to prevent a decrease in color developability. This is a colorant pigment in which a poorly water-soluble 1,2-alkanediol, which is an oily substance, permeates the fiber of plain paper selectively permeates, swells the fiber, and is dispersed in a water-soluble component. It is thought that the penetration between the fiber layers is hindered.

  In the present invention, the water-soluble 1,2-alkanediol is preferably a 1,2-alkanediol having 5 or 6 carbon atoms which may have a branch, and 4-methyl-1,2-pentanediol, 1 , 2-pentanediol, 3,3-dimethyl-1,2-butanediol, 1,2-hexanediol. Among these, it is particularly preferable to use 1,2-hexanediol and / or 4-methyl-1,2-pentanediol.

  The water-soluble 1,2-alkanediol is preferably contained in an amount of 3% by weight or more, more preferably 3 to 15% by weight, based on the entire ink composition. By setting it as this range, the separation of the poorly water-soluble 1,2-alkanediol can be suppressed, and the ejection becomes stable.

  As the poorly water-soluble 1,2-alkanediol, those having 1,2-alkanediol having 8 or more carbon atoms which may have a branch are preferably used, and 4,4-dimethyl-1,2 -Pentanediol, 5-methyl-1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol. In particular, it is preferable to use 1,2-octanediol.

  The slightly water-soluble 1,2-alkanediol is preferably contained in an amount of 0.3 to 15.0% by weight, more preferably 0.3 to 3.0% by weight, based on the entire ink composition. It is more preferable. By setting it as this range, the separation of the poorly water-soluble 1,2-alkanediol can be suppressed, and the ejection becomes stable. Moreover, even if it does not contain the water-soluble 1,2-alkanediol in an amount exceeding 15 wt%, the surface tension can be made extremely low, which is effective in reducing the viscosity, suppressing aggregation, and storage stability. For example, the surface tension of an aqueous solution containing 7 wt% 4-methyl-1,2-pentanediol and 3 wt% 1,2-octanediol is 25 mN / m or less.

  In the present invention, the content ratio of the water-soluble 1,2-alkanediol and the slightly water-soluble 1,2-alkanediol is preferably 10: 1 to 1: 1 on a weight basis. By setting the mixing ratio within this range, separation of the poorly water-soluble 1,2-alkanediol can be suppressed, and the ejection becomes stable. Moreover, the strike-through and / or aggregation spots can be further reduced.

  Furthermore, in the present invention, the penetrating solvent includes 1.2-alkanediol having 5 to 10 carbon atoms and / or lactams and / or lactones to which a polyoxyethylene chain and / or a polypropylene chain is added. You may go out.

<Surfactant>
The ink composition for inkjet recording according to the present invention contains a surfactant as an essential component. Glossy recording media such as photographic paper, where glossiness is more important by using a surfactant, compared to a recording medium coated with a resin for receiving ink on the surface. Can be realized. In particular, even when a recording medium having a coating layer for receiving oil-based ink is provided on the surface receiving layer, such as printing paper, bleeding between colors (bleeding) can be prevented. At the same time, it is possible to prevent whitening due to reflected light of light generated with an increase in the amount of ink attached.

  Further, the penetrating solvent may contain 1.2-alkanediol having 5 to 10 carbon atoms and / or lactams and / or lactones to which polyoxyethylene chains and / or polypropylene chains are added.

<Surfactant>
The ink composition for inkjet recording according to the present invention contains a surfactant as an essential component. Glossy recording media such as photographic paper, where glossiness is more important by using a surfactant, compared to a recording medium coated with a resin for receiving ink on the surface. Can be realized. In particular, even when a recording medium having a coating layer for receiving oil-based ink is provided on the surface receiving layer, such as printing paper, bleeding between colors (bleeding) can be prevented. At the same time, it is possible to prevent whitening due to reflected light of light generated with an increase in the amount of ink attached.

  As the surfactant used in the present invention, an organopolysiloxane surfactant is used. When an organopolysiloxane surfactant is used, it contains two specific types of alkanediol as described above, so that the solubility of the surfactant in the ink is improved and the generation of insoluble matter can be suppressed. Therefore, it is possible to realize an ink composition with more excellent ejection stability.

（式中、Ｒは水素原子またはメチル基を表し、ａは７〜１１の整数を表し、ｍは２０〜７０の整数を表し、ｎは２〜５の整数を表す。）
で表される一種ままたは二種以上の化合物を含んでなることがより好ましい。このような特定のオルガノポリシロキサン系界面活性剤を使用することにより、より一層インクの凝集むらが改善できる。 In addition, as an organopolysiloxane surfactant, the following formula:

(In the formula, R represents a hydrogen atom or a methyl group, a represents an integer of 7 to 11, m represents an integer of 20 to 70, and n represents an integer of 2 to 5).
More preferably, it comprises one or more compounds represented by the formula: By using such a specific organopolysiloxane surfactant, the unevenness of ink aggregation can be further improved.

  As another preferred embodiment of the present invention, in the polysiloxane compound represented by the above formula, R represents a hydrogen atom or a methyl group, a represents an integer of 2 to 5, and m represents an integer of 20 to 70. N represents an integer of 2 to 4 and may contain one or more compounds.

  Moreover, when it contains each said polyorganosiloxane compound, as a surfactant, in said formula, R represents a hydrogen atom or a methyl group, a represents the integer of 9-13, m represents 2-4. It represents an integer, and n preferably contains a polysiloxane compound represented by 1 or 2. By using such a polysiloxane compound in combination, the unevenness of ink aggregation can be further improved.

  The reason why the uneven aggregation of the ink can be improved by containing the specific polyorganosiloxane compound as described above is considered as follows. That is, for example, in an aqueous solution containing 20 wt% glycerin (glycerol), 10 wt% 1.2-hexanediol, and 0.1 wt% of the above surfactant, the surface tension at 1 Hz of the aqueous solution is 25 mN / m or less. It is considered that this is because the aqueous solution containing glycols can have an extremely low surface tension by containing the above surfactant. The surface tension of Surfynol 465, which is an acetylene glycol surfactant, is 25 mN / m or more when an aqueous solution having the same composition as described above is used.

  Commercially available surfactants such as those described above may be used. For example, KF-954A, KF-353A, KF6017, X-22-6551, AW-3 (all manufactured by Shin-Etsu Chemical Co., Ltd.) Etc. can be used.

  The surfactant is preferably contained in the ink composition according to the present invention in an amount of 0.01 to 2.00% by weight, more preferably 0.05 to 0.50% by weight. In particular, when the above-mentioned surfactant in which R is a methyl group is used, it is preferable to increase the content as compared with the case in which the above-described surfactant in which R is H.

  The ink composition according to the present invention further includes other surfactants, specifically, a fluorine-based surfactant, an acetylene glycol-based surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like. It may be added.

  Among these, acetylene glycol surfactants include, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6- Diol, or 3,5-dimethyl-1-hexyn-3ol, 2,4-dimethyl-5-hexyn-3-ol and the like can be mentioned. Commercially available acetylene glycol surfactants can also be used. For example, Olphine E1010, STG, Y (trade name, manufactured by Nissin Chemical Co., Ltd.), Surfynol 61, 104, 82, 465, 485 or TG (Trade name, manufactured by Air Products and Chemicals Inc.).

<Colorant>
As the colorant used in the ink composition for ink jet recording according to the present invention, both dyes and pigments can be used, and pigments can be preferably used from the viewpoint of light resistance and water resistance.

  As the pigment, inorganic pigments and organic pigments can be used, and each can be used alone or in combination. As the inorganic pigment, for example, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Examples of the organic pigment include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used.

  Specific examples of the pigment are appropriately given according to the type (color) of the ink composition to be obtained using the pigment dispersion according to the present invention. For example, as a pigment for a yellow ink composition, C.I. I. Pigment Yellow 1, 2, 3, 12, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 128, 129, 138, 139, 147, 150, 151, 154, 155, 180, 185 and the like, and one or more of these are used. Of these, C.I. I. It is preferable to use one or more selected from the group consisting of CI Pigment Yellow 74, 110, 128 and 147. Examples of the pigment for the magenta ink composition include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 209; I. Pigment violet 19 or the like, and one or more of these may be used. Of these, C.I. I. Pigment red 122, 202, 209 and C.I. I. It is preferable to use one or more selected from the group consisting of CI Pigment Violet 19. Examples of the pigment for the cyan ink composition include C.I. I. Pigment Blue 1, 2, 3, 15: 2, 15: 3, 15: 4, 15:34, 16, 22, 60; I. Bat blue 4, 60, etc. are mentioned, These 1 type or 2 types or more are used. Of these, C.I. I. Pigment Blue 15: 3 and / or 15: 4 are preferably used, especially C.I. I. Pigment Blue 15: 3 is preferably used. Examples of the pigment for the black ink composition include carbon blacks such as furnace black, lamp black, acetylene black and channel black (CI pigment black 7), inorganic pigments such as iron oxide pigments; aniline black And organic pigments such as (CI Pigment Black 1).

  In the present invention, the pigment is preferably a pigment kneaded with a dispersant described later, and an excellent color image can be formed even if the pigment is not surface-treated.

<Dispersant>
The ink composition according to the present invention preferably comprises a copolymer resin of a hydrophobic monomer and a hydrophilic monomer as a dispersant for dispersing the colorant. These copolymer resins are adsorbed on the pigment to improve dispersibility.

  Specific examples of the hydrophobic monomer include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, iso-propyl acrylate, iso-propyl methacrylate, n-butyl acrylate, and n-butyl. Methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, iso-octyl acrylate, iso-octyl Methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate, laur Methacrylate, stearyl acrylate, stearyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylamino Ethyl acrylate, 2-diethylaminoethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, allyl acrylate, allyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, nonyl phenyl acrylate, nonyl phenyl methacrylate, benzyl acrylate, benzyl methacrylate, dicyclo Pentenyl acrylate, dicyclopentenyl methacrylate, bornyl acrylate, bornyl methacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol di Methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene Glycol dimethacrylate, neopentyl glycol diacrylate, 1,6 Hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerol acrylate, glycerol methacrylate, styrene, methylstyrene, vinyl Toluene and the like can be mentioned. These may be used alone or in admixture of two or more.

  Specific examples of the hydrophilic monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like.

  From the viewpoint that the copolymer resin of the hydrophobic monomer and the hydrophilic monomer can form a color image having both glossiness of the color image, prevention of bronzing, and storage stability of the ink composition and excellent glossiness. , Styrene- (meth) acrylic acid copolymer resin, styrene-methylstyrene- (meth) acrylic acid copolymer resin, or styrene-maleic acid copolymer resin, (meth) acrylic acid- (meth) acrylic acid ester copolymer resin Or at least one of styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer resin.

  The copolymer resin may be a resin (styrene-acrylic acid resin) containing a polymer obtained by reacting styrene with acrylic acid or an ester of acrylic acid. Alternatively, the copolymer resin may be an acrylic acid-based water-soluble resin. Alternatively, a salt such as sodium, potassium, or ammonium may be used.

  The content of these copolymer resins is 100 parts by weight of the pigment from the viewpoint of achieving color image glossiness, prevention of bronzing, and storage stability of the ink composition and forming a color image with further excellent glossiness. The amount is preferably 10 to 50 parts by weight, and more preferably 10 to 35 parts by weight.

  Examples of surfactants preferable as a dispersant include fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfate esters, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfosuccinate esters, naphthenes. Anionic surfactants such as acid salts, liquid fatty oil sulfate esters, alkylallyl sulfonates; cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts, phosphoniums; polyoxyethylene alkyl ethers And nonionic surfactants such as polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and the like. It goes without saying that the above-mentioned surfactant is added to the ink composition, so that it also functions as a surfactant. However, it is necessary to add the surfactant so that the contact angle with the recording medium falls within the above range. is there.

(3) Water and other components The ink composition for ink jet recording according to the present invention contains the above-described specific solvent, surfactant, and other various additives, and also contains water as a solvent. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria is prevented over a long period of time.

  The ink composition for inkjet recording according to the present invention may further contain an organic amine. When forming a recorded image, the wettability of the recording medium or the like to the recording surface can be increased to increase the ink permeability, and the pH of the ink composition can be easily adjusted to a suitable range. . As the organic amine, a tertiary amine can be preferably used.

  Examples of the tertiary amine include alkanolamines such as triethanolamine. The ink composition according to the present invention preferably has a pH of 8 to 12, particularly 8 to 10. When the pH is within such a range, deterioration of the member in contact with the ink can be prevented.

  The content of the organic amine with respect to the total weight of the ink composition is 0.1% by weight or more. However, when forming a recorded image, the wettability of the recording medium or the like to the recording surface is improved to increase the ink permeability. And from the viewpoint of ink ejection stability, storage stability, and high-speed printing, it is preferably 0.1 to 8.0% by weight, more preferably 0.5 to 5.0% by weight, and still more preferably Is 1.0 to 3.0% by weight.

  The ink composition according to the present invention preferably contains a penetrant in addition to the above components.

  As the penetrant, glycol ethers can be preferably used.

  Specific examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert -Butyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-iso-propyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-tert-butyl ether, triethylene Glycol mono-n-bu Ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-tert-butyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol-iso-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-tert-butyl ether, 1-methyl -1-methoxybutanol and the like, and one or a mixture of two or more thereof It is possible to have.

  Among the glycol ethers, alkyl ethers of polyhydric alcohols are preferable, and ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, triethylene are particularly preferable. Glycol monomethyl ether, triethylene glycol monoethyl ether or triethylene glycol mono-n-butyl ether is preferred. More preferred is triethylene glycol mono-n-butyl ether.

  The addition amount of the penetrant may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 1 to 20% by weight.

The ink composition according to the present invention preferably contains a recording medium solubilizer in addition to the above components.

  As the recording medium solubilizer, pyrrolidones such as N-methyl-2-pyrrolidone and / or lactones such as γ-butyrolactone can be preferably used. The addition amount of the recording medium solubilizer may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 1 to 20% by weight.

The ink composition for ink jet recording according to the present invention preferably contains a wetting agent. As the wetting agent, polyhydric alcohols and / or saccharides can be preferably used. Specific examples of the polyhydric alcohols include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane and the like. Specific examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, Examples include glucitol, (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature, such as alginic acid, α-cyclodextrin, and cellulose. The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above (for example, sugar alcohol (general formula HOCH ₂ (CHOH) _n CH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thiosaccharides, etc.). Particularly preferred are sugar alcohols, and specific examples include maltitol, sorbitol, xylitol and the like. As a commercially available product, HS500 (manufactured by Hayashibara Shoji) can also be suitably used. As the hyaluronate, a commercially available sodium hyaluronate 1% aqueous solution (molecular weight 350,000) can be used. Trimethylolpropane and 1,2,6-hexatriol can also be suitably used.

  Although the addition amount of the wetting agent may be appropriately determined, it is preferably 0.1 to 30% by weight, more preferably about 1 to 20% by weight, and further preferably 6 to 16% by weight. In addition, it will be apparent to those skilled in the art that some of the penetrating solvents described above also act as wetting agents.

  The ink composition according to the present invention may further contain a nozzle clogging preventive agent, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorber, and the like. it can.

  Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzthiazoline-3-one ( ICI's Proxel CRL, Proxel BND, Proxel GXL, Proxel XL-2, Proxel TN) and the like.

  Furthermore, examples of pH adjusters, solubilizers or antioxidants include amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, potassium hydroxide, sodium hydroxide, lithium hydroxide, etc. Inorganic salts, ammonium hydroxide, quaternary ammonium hydroxide (tetramethylammonium, etc.), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate and other phosphates, or N-methyl-2-pyrrolidone, urea, thiourea And L-ascorbic acid and salts thereof, such as ureas such as tetramethylurea, allophanates such as allophanate and methylallohanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret.

  In addition, the ink composition according to the present invention may contain an antioxidant and an ultraviolet absorber. Examples thereof include Tinuvin 328, 900, 1130, 384, 292, 123, and 144 manufactured by Ciba Specialty Chemicals. 622, 770, 292, Irgacor 252 153, Irganox 1010, 1076, 1035, MD1024, lanthanide oxide, and the like.

  The ink composition according to the present invention can be produced by dispersing and mixing each of the above components by an appropriate method. Preferably, the pigment, polymer dispersant, and water are first used in a suitable dispersing machine (for example, ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc.). Mix to prepare a uniform pigment dispersion, then add separately prepared resin (resin emulsion), water, water-soluble organic solvent, sugar, pH adjuster, preservative, fungicide, etc. An ink solution is prepared. After sufficiently stirring, the target ink composition can be obtained by performing filtration in order to remove the coarse particle diameter and foreign matters that cause clogging.

Inkjet recording method An inkjet recording method according to the present invention ejects droplets of the ink composition described above, and attaches the droplets to a recording medium for printing, and the ejected ink droplets overlap with each other. In this way, it is attached to the recording medium. In the recording method according to the present invention, it is preferable to use printing paper as a recording medium. Even when such a specific recording medium is used, an image having excellent gloss and good color reproducibility can be realized.

  Further, in the ink jet recording method of the present invention, it is preferable that the ink composition droplets are ejected so that the dot arrangement in the direction perpendicular to the scanning direction of the recording head is alternately arranged. When dots are formed so as to have such a checkered pattern arrangement, the use of the ink composition of the present invention described above significantly improves the unevenness of aggregation as compared with the conventional ink composition.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

なお、表中のスチレンーアクリル酸系樹脂は、分子量１６００、酸価１５０の共重合体である。 <Preparation of ink composition>
Each ink was prepared by mixing each component according to the composition of Table 1 below and filtering through a 10 μm membrane filter.

The styrene-acrylic acid resin in the table is a copolymer having a molecular weight of 1600 and an acid value of 150.

<Evaluation>
Using a discharge-stable ink jet printer (PX-G900, manufactured by Seiko Epson Corporation), solid and line patterns were continuously printed at 5 ° C. (low temperature) in the recommended clean mode of photographic paper for each ink. Ink printing was observed for missing dots and flying curves within 1000 pages of printing, and evaluation was performed based on the following criteria.
A: There is no missing dot or flying curve.
B: No more than 10 missing dots or flying bends.
C: There are more than 10 missing dots and flying bends.

  The evaluation results were as shown in Table 2 below.

Clogging recovery evaluation Using the above ink jet printer, after filling each head into the head and confirming that the ink is discharged from all the nozzles, in order to accelerate the drying state at the nozzles, The recording head was removed from the head cap and left in an environment of 40 ° C. and 20% RH for one week.

After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria.
A: Recovered to the same level as the initial stage after 3 cleaning operations.
B: Recovered to the same level as the initial stage after 6 cleaning operations.
C: After 6 cleaning operations, left for 6 hours, and then recovered to the same level as the initial stage after another cleaning.

  The evaluation results were as shown in Table 2 below.

Ink cartridge 1 is mounted on an ink cartridge of an ink jet printer similar to the above, and “plain paper recommended clean mode” is selected, and “no gloss optimizer” is set to Xerox 4024 paper (manufactured by Xerox Corporation) 720 After solid printing at a resolution of × 720 dpi and leaving at 25 ° C. for 24 hours, the OD value of the recording surface was measured using an SPM50 manufactured by Gretag. The color developability of the image was evaluated based on the following criteria.
A: OD value is 1.2 or more B: OD value is 1.1 or more and less than 1.2 C: OD value is less than 1.1

  Similarly, the color reproducibility was also evaluated for ink sets 2 to 9. The evaluation results were as shown in Table 2.

The ink set 1 is attached to the bleed-through ink cartridges of the same ink jet printer, select "Photo Paper Recommended beautiful mode", the setting of "no gloss optimizer", Xerox 4024 to the paper (manufactured by Xerox Corp.), 1440 After solid printing at a resolution of × 720 dpi and leaving at 25 ° C. for 24 hours, the OD value on the back side of the recording surface was measured using SPM50 manufactured by Gretag. The degree of strike-through was evaluated based on the following criteria.
A: OD value is less than 0.06 B: OD value is 0.06 or more

  Similarly, the color reproducibility was also evaluated for ink sets 2 to 9. The evaluation results were as shown in Table 2.

Ink aggregation unevenness In each of the inks obtained above, the ink set 1 is mounted on an ink cartridge of an ink jet printer similar to the above, and OK Top Coat Plus (made by Oji Paper Co., Ltd.) which is the main printing paper has a resolution of 1440 × 1440 dpi. The printing was done. As the printing conditions at this time, the ink ejection amount was adjusted so that the dot weight would be 7 ng in the unidirectional recording method in which the resolution of 720 × 180 dpi is obtained by one drive of the recording head. The driving head is 200 cps.

The obtained recorded matter was evaluated for unevenness of ink aggregation according to the following criteria.
AA: 5.2 mg / in ink weight of inch ^2, no uneven coagulation A: 4.4 mg / in ink weight of inch ^2, but there is no uneven coagulation, the ink weight of 5.2 mg / inch ^2, aggregation occurs To do.
B: Even when the ink weight is 3.6 mg / inch ² , there is no uneven aggregation, but when the ink weight is 4.4 mg / inch ² , aggregation occurs.
C: Even at an ink weight of 3.6 mg / inch ² , aggregation unevenness occurs.

Similarly, the aggregation unevenness was also evaluated for ink sets 2 to 9. The evaluation results were as shown in Table 2.

Claims (14)

An ink composition for ink-jet recording comprising at least a colorant, water, alkanediol, and a surfactant,
The alkanediol comprises a water-soluble 1,2-alkanediol and a poorly water-soluble 1,2-alkanediol;
An ink composition for ink jet recording, wherein the surfactant is polyorganosiloxane.   The ink composition for inkjet recording according to claim 1, wherein the water-soluble 1,2-alkanediol is a 1,2-alkanediol having 5 or 6 carbon atoms which may have a branch.   The ink composition for inkjet recording according to claim 2, wherein the water-soluble 1,2-alkanediol is 1,2-hexanediol and / or 4-methyl-1,2-pentanediol.   The inkjet recording according to any one of claims 1 to 3, wherein the poorly water-soluble 1,2-alkanediol is a 1,2-alkanediol having 7 to 10 carbon atoms which may have a branch. Ink composition.   The ink composition for inkjet recording according to claim 4, wherein the poorly water-soluble 1,2-alkanediol is 1,2-octanediol. The polyorganosiloxane has the following formula:

(In the formula, R represents a hydrogen atom or a methyl group, a represents an integer of 7 to 11, m represents an integer of 20 to 70, and n represents an integer of 2 to 5).
The ink composition for inkjet recording according to any one of claims 1 to 5, comprising one or more compounds represented by the formula: The polyorganosiloxane has the following formula:

(In the formula, R represents a hydrogen atom or a methyl group, a represents an integer of 2 to 5, m represents an integer of 20 to 70, and n represents an integer of 2 to 4).
The ink composition for inkjet recording according to any one of claims 1 to 5, comprising one or more compounds represented by the formula: The ink composition for inkjet recording according to claim 6 or 7, further comprising a polyorganosiloxane represented by the following formula as a surfactant.

(In the formula, R represents a hydrogen atom or a methyl group, a represents an integer of 9 to 13, m represents an integer of 2 to 4, and n represents 1 or 2.)   The ink composition for ink jet recording according to any one of claims 1 to 8, wherein the water-soluble 1,2-alkanediol is contained in an amount of 3% by weight or more based on the whole ink composition.   The ink composition for inkjet recording according to any one of claims 1 to 9, wherein the slightly water-soluble 1,2-alkanediol is contained in an amount of 0.3% by weight or more based on the whole ink composition.   The ratio of the addition amount of the water-soluble 1,2-alkanediol and the poorly water-soluble 1,2-alkanediol is 10: 1 to 1: 1. An ink composition for ink jet recording described in 1.   An inkjet recording method for performing printing by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink composition for inkjet recording according to any one of claims 1 to 11 is used. An ink jet recording method to be used.   The method according to claim 12, wherein the recording medium is printing paper.   A recorded matter recorded by the ink jet recording method according to claim 12 or 13.